Logical backup

Logical backups are backups in which the export utility (for example exp)
uses SQL to read database data and then export it into a binary file at the operating system level. You can then
import the data back into a database using the import utility (imp).

Backups taken with the export utility differ in the following ways from RMAN backups:

Database logical objects are exported independently of the files that contain those objects.

Logical backups can be imported into a different database, even on a different platform. RMAN backups are not portable between databases or platforms.

Usually, physical backups are made. However, if a backup needs to copy a database to a different OS, a logical backup needs be made (Not always true anymore in 10g.)